Project Summary
Caltrans, other state agencies, and local agencies are increasingly planning and building under- and over-crossing structures for wildlife to traverse busy highways. Several criteria are key for the success of these structures: sufficient safety and/or conservation need, cost, location, and anticipated use by wildlife. Although transportation agency biologists are aware of the potential for traffic noise and light to impede structure use by wildlife, few tools are available to inform designers, engineers, architects and habitat designers of the structural and vegetation elements that could reduce disturbance. The project is intended to support the implementation of California’s Transportation Plan 2040, which states that “Early consultation and evaluation of environmental resources … helps to identify environmental impacts of planned infrastructure projects and early opportunities to avoid natural resource impacts, and guide mitigation and planning decision-making.” (p. 110) Research has found that higher traffic noise and to some degree light are correlated with decreased species presence at crossing structures, particularly for certain species (e.g. predators) that seem more sensitive. The research team will carry out fine-scale investigations of traffic noise and light adjacent to proposed crossing structures and existing structures not built for wildlife, but used by wildlife to cross highways. For certain structures, the research team will work with Caltrans, landscape designers, and local organizations to model an approach zone to the structure that has reduced noise and light disturbance.
